The World Health Organization says polio vaccines it is using in Nigeria are safe and untainted. Islamic clerics in the states of Kaduna, Kano, and Zamfara suspended the polio immunization programs on Sunday, claiming the vaccine is unsafe.

The Nigerian Islamic clerics say the vaccine used in WHO's polio campaign is contaminated with substances that can cause HIV/AIDS, cancers, and sterility in women.

The Head of WHO's Global Polio Eradication Program, David Heymann, said he has been aware of these concerns for the last three or four weeks. He said he has made several trips to the area, and has looked at the vaccines that the Islamic groups reject as unsafe. "I have to say that our vaccines are pure vaccines, provided by UNICEF to countries working on polio eradication, and the same vaccines are used throughout the world. So, we are sure that these vaccines are pure. We understand that there have been some findings that might suggest that there would be elements of hormones, female hormones or family planning elements in the vaccine. But, our studies have not shown that to be the case. All the vaccine comes from manufacturers who are pre-qualified by WHO," he said.

The Nigerian Islamic clerics say immunizations against polio will be suspended, until an investigation into the purity of the vaccine is completed. WHO says it is concerned that this position could adversely affect its efforts to eradicate polio around the world by the end of 2005.

Dr. Heymann said about 13 percent of the children in the three northern Nigerian States have been immunized against polio. He said more than 100 children have been paralyzed because of lack of vaccination.

In an ominous sign, he said, cases of polio spread from northern Nigeria to the center and south of the country, even to the city of Lagos with its 10 million inhabitants.

"In addition, polio has been exported to neighboring countries - Ghana, Niger, Burkina Fasso, Togo, and possibly Chad," he said. "We are just confirming the Chad viruses now. So, what is happening is that Nigeria, by not controlling polio in the north, has become a focus of exporting the virus to countries, which are polio free. This is causing paralysis of children in those countries, and in addition is costing about $13 to $14 million to put up the firewalls of immunity to protect those countries from having polio establish itself again."

Dr. Heymann said Islamic heads of state passed a resolution making polio eradication a priority at the Organization of Islamic Conference 12 days ago in Malaysia. He said indigenous polio is present in only seven countries around the world. Six of them are Islamic countries.